Photoionization techniques, in which ionization comes about by the action of radiant energy, have relatively recently come into use, particularly in connection with laser isotope separation. In this regard, reference may be made to U.S. Pat. No. 4,379,252 and articles from "Laser Focus", September 1982 Issue, pps. 49-54 by David, et al of the Lawrence Livermore National Laboratory, and "Photonics Spectra", October, 1982 Issue, pps. 49-66 and entitled "Lasers in Chemistry" by Chen et al. These articles along with other known techniques rely upon the use of a pulsed laser beam for photoionization so as to bring the isotope that is to be enriched from the lowest energy state (ground state), directly to the photoionized state. The present techniques as they relate to the energy level diagram of FIG. 1 herein, teach a transition directly from the ground 6.sup.1 S.sub.0 state to the 6.sup.3 P.sub.1 state, and from there directly to the 7.sup.3 S.sub.1 state and subsequently into an ionized state. However, this requires the use of a relatively high power laser source and makes the entire procedure relatively costly.